Field of the Invention
The present disclosure relates to an electrophotographic photosensitive member, a process cartridge, and an electrophotographic apparatus.
Description of the Related Art
In an electrophotographic process, the surface of the electrophotographic photosensitive member mounted in an electrophotographic apparatus will come in contact with a developer, a printing medium (paper), a charging member, a transfer member, a cleaning member, and the like. Accordingly, as the number of printed sheets is increased, the surface of the electrophotographic photosensitive member is more worn or damaged. This can affect the image quality of resulting graphics or text. In recent years, high-volume printing and high-speed printing have been required of electrophotographic processes. Accordingly, even though an electrophotographic photosensitive member has such a durability that it can be kept from being worn or damaged by contact when the number of printed sheets is that in conventional printing, the electrophotographic photosensitive member is required to have higher durability. Accordingly, Japanese Patent Laid-Open Nos. 10-20514, 2006-53549, and 2011-7914 disclose techniques using a photosensitive member including a surface layer made of a polyester resin having a high mechanical strength. Japanese Patent Laid-Open Nos. 10-20514 and 2006-53549 disclose an electrophotographic photosensitive member including a surface layer made of a polyester resin containing a diphenyl ether dicarboxylic acid moiety. Japanese Patent Laid-Open No. 2011-7914 discloses an electrophotographic photosensitive member including a surface layer made of a polyester resin containing a divalent phenol derivative containing three or more aromatic rings that are connected to each other. Any of these disclosures describes that the durability of the electrophotographic photosensitive member is improved.